U.S. patent application number 13/251067 was filed with the patent office on 2013-04-04 for offline low voltage dc output circuit with integrated full bridge rectifiers.
This patent application is currently assigned to Monolithic Power Systems, Inc.. The applicant listed for this patent is Joseph Urienza. Invention is credited to Joseph Urienza.
Application Number | 20130083577 13/251067 |
Document ID | / |
Family ID | 47446967 |
Filed Date | 2013-04-04 |
United States Patent
Application |
20130083577 |
Kind Code |
A1 |
Urienza; Joseph |
April 4, 2013 |
OFFLINE LOW VOLTAGE DC OUTPUT CIRCUIT WITH INTEGRATED FULL BRIDGE
RECTIFIERS
Abstract
The present disclosure discloses an offline low voltage DC
output circuit with integrated full bridge rectifiers. The offline
low voltage DC output circuit comprises two depletion high voltage
pass transistors and a bridge rectifier, wherein most of the
voltage is dropped across the pass transistor device. In one
embodiment, the offline low voltage DC output circuit further
comprises a ballast resistor to minimize substrate injection.
Inventors: |
Urienza; Joseph; (Milpitas,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Urienza; Joseph |
Milpitas |
CA |
US |
|
|
Assignee: |
Monolithic Power Systems,
Inc.
|
Family ID: |
47446967 |
Appl. No.: |
13/251067 |
Filed: |
September 30, 2011 |
Current U.S.
Class: |
363/126 ;
257/272; 257/E27.069; 716/119 |
Current CPC
Class: |
H02M 7/217 20130101;
H02M 7/2176 20130101; H01L 27/098 20130101 |
Class at
Publication: |
363/126 ;
257/272; 716/119; 257/E27.069 |
International
Class: |
H02M 7/21 20060101
H02M007/21; G06F 17/50 20060101 G06F017/50; H01L 27/098 20060101
H01L027/098 |
Claims
1. An offline low voltage DC output circuit, comprising: a first
input port and a second input port configured to receive an input
AC voltage; an output port configured to provide an output voltage;
a first depletion high voltage pass transistor coupled to the first
input port to receive the input AC voltage, and based on the input
AC voltage, the first depletion high voltage pass transistor
provides a first voltage; a second depletion high voltage pass
transistor coupled to the second input port to receive the input AC
voltage, and based on the input AC voltage, the second depletion
high voltage pass transistor provides a second voltage; and a
bridge rectifier having a first input terminal, a second input
terminal, and an output terminal, wherein the first input terminal
is coupled to the first depletion high voltage pass transistor to
receive the first voltage, the second input terminal is coupled to
the second depletion high voltage pass transistor to receive the
second voltage, and wherein the output terminal is coupled to the
output port.
2. The offline low voltage DC output circuit of claim 1, wherein
the first depletion high voltage pass transistor and the second
depletion high voltage pass transistor each having a gate coupled
to ground.
3. The offline low voltage DC output circuit of claim 1, wherein
the first depletion high voltage pass transistor and the second
depletion high voltage pass transistor each having a substrate
coupled to ground via a ballast resistor.
4. The offline low voltage DC output circuit of claim 3, wherein
the ballast resistor comprises a poly resistor or any non-diffusion
type resistor.
5. The offline low voltage DC output circuit of claim 1, wherein
the first depletion high voltage pass transistor comprises a first
depletion high voltage JFET; and the second depletion high voltage
pass transistor comprises a second depletion high voltage JFET.
6. The offline low voltage DC output circuit of claim 1, wherein
the first depletion high voltage pass transistor and the second
depletion high voltage pass transistor each having a substrate
coupled to ground via an active circuit.
7. The offline low voltage DC output circuit of claim 6, wherein
the active circuit comprises a negative charge pump.
8. The offline low voltage DC output circuit of claim 1, wherein
the bridge rectifier further comprises a fourth terminal coupled to
ground.
9. An offline low voltage DC output integrated circuit die
comprising: a plurality of minority generating devices; a plurality
of mergeable NWell; a plurality of unmergeable devices: a first
site, and a second site, wherein the first site and the second site
are placed on opposite sides of the integrated circuit die; an
N-well tub between the first site and the second site; and a die
seal; wherein the minority generating devices are placed at the
first site and the second site; the devices with mergeable NWell
are group together and placed in the N-well tub; and the
unmergeable devices are placed next to the die seal or close to an
edge of the integrated circuit die.
10. The integrated circuit die of claim 9, wherein the N-well tub
serves as a minority collector; and the edge of the integrated
circuit die serves as a recombination site for minority
carriers.
11. The integrated circuit die of claim 10, wherein the minority
collector further comprises a N-type buried layer.
12. The integrated circuit die of claim 9, wherein the minority
generating devices comprise a first depletion high voltage pass
transistor and a second depletion high voltage pass transistor.
13. A method for a layout scheme for the integrated circuit die as
claimed in claim 9, characterized that the method comprises:
placing minority generating devices at a first site and a second
site; wherein the first site and the second site are placed on
opposite sides of the integrated circuit die; placing devices with
mergeable NWell into a N-Well tub, wherein the N-well tub serves as
a minority collector; placing unmergeable devices next to a die
seal or close to a die edge; placing sensitive devices as far as
possible from the first site and the second site; and surrounding
unmergeable devices with the minority collector.
14. The integrated circuit die of claim 12, wherein the minority
generating devices comprise a first depletion high voltage pass
transistor and a second depletion high voltage pass transistor.
15. A method for providing a low voltage DC output from an AC
offline source, comprising: receiving an AC input voltage;
generating a first voltage in response to the AC input voltage;
generating a second voltage in response to the AC input voltage;
and generating a low voltage DC output by rectifying the first
voltage and the second voltage.
16. The method of claim 15, wherein the rectifying is executed by a
bridge rectifier.
17. The method of claim 15, wherein the first voltage is generated
by a first depletion pass transistor; and the second voltage is
generated by a second depletion pass transistor.
18. The method of claim 15, wherein both the first depletion pass
transistor and the second depletion pass transistor have a
substrate connected to ground via a ballast resistor.
19. The method of claim 15, wherein both the first depletion pass
transistor and the second depletion pass transistor have a
substrate connected to ground via an active circuit.
20. The method of claim 19, wherein the active circuit comprises a
charge pump.
Description
FIELD
[0001] The present disclosure relates to offline integrated
circuits, more particularly, the present disclosure relates to
offline AC-low voltage full-wave rectified DC output integrated
bridge circuits.
BACKGROUND OF THE DISCLOSURE
[0002] Sometimes in low power offline applications, rectified
output voltage is needed which may be used to power small logic
signal, boot/wake-up startup circuits, transponders, sensor
circuits, small relays, etc.
[0003] FIG. 1 illustrates a schematic circuit of a prior art
offline low voltage rectified DC output circuit 50. The circuit 50
comprises a transformer which receives an input AC voltage, and
based on the input AC voltage, the transformer provides a step-down
AC voltage; and a bridge which receives the step-down AC voltage,
and based on the step-down AC voltage, the bridge rectifier
provides a rectified DC output waveform.
[0004] However, such circuit 50 needs a transformer to step down
the input AC voltage, which highly increases the system volume,
weight and cost.
[0005] So there is a need to provide a simpler and cost effective
integrated circuit (semiconductor approach) of offline AC-low
voltage DC rectification.
SUMMARY
[0006] It is an object of the present disclosure to provide a
circuit and a method for constant current regulation of power
supplies.
[0007] In accomplishing the above and other objects, there has been
provided, in accordance with an embodiment of the present
disclosure, an offline low voltage DC output circuit, comprising: a
first input port and a second input port configured to receive an
input AC voltage; an output port configured to provide an output
voltage; a first depletion high voltage pass transistor coupled to
the first input port to receive the input AC voltage, and based on
the input AC voltage, the first depletion high voltage pass
transistor provides a first voltage; a second depletion high
voltage pass transistor coupled to the second input port to receive
the input AC voltage, and based on the input AC voltage, the second
depletion high voltage pass transistor provides a second voltage;
and a bridge rectifier having a first input terminal, a second
input terminal, and an output terminal, wherein the first input
terminal is coupled to the first depletion high voltage pass
transistor to receive the first voltage, the second input terminal
is coupled to the second depletion high voltage pass transistor to
receive the second voltage, and wherein the output terminal is
coupled to the output port.
[0008] In addition, there has been provided, in accordance with an
embodiment of the present disclosure, an offline low voltage DC
output integrated circuit die comprising: a plurality of minority
generating devices; a plurality of mergeable NWell; a plurality of
unmergeable devices: a first site, and a second site, wherein the
first site and the second site are placed on opposite sides of the
integrated circuit die; an N-well tub between the first site and
the second site; and a die seal; wherein the minority generating
devices are placed at the first site and the second site; the
devices with mergeable NWell are group together and placed in the
N-well tub; and the unmergeable devices are placed next to the die
seal or close to an edge of the integrated circuit die.
[0009] Furthermore, there has been provided, in accordance with an
embodiment of the present disclosure, a method for providing a low
voltage DC output from an AC offline source, comprising: receiving
an AC input voltage; generating a first voltage in response to the
AC input voltage; generating a second voltage in response to the AC
input voltage; and generating a low voltage DC output by rectifying
the first voltage and the second voltage.
[0010] These and other features of the present disclosure will be
readily apparent to persons of ordinary skill in the art upon
reading the entirety of this disclosure, which includes the
accompanying drawings and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 illustrates a schematic circuit of a prior art
offline AC-low voltage rectified DC output circuit 50.
[0012] FIG. 2 illustrates a schematic circuit of an offline AC-low
voltage rectified DC output circuit 100 in accordance with an
embodiment of the present disclosure.
[0013] FIG. 3 schematically illustrates the output voltage
(V.sub.O) and the input AC voltage (AC) in the offline AC-low
voltage rectified DC output circuit 100 in FIG. 2.
[0014] FIG. 4 schematically illustrates a layout scheme of a
typical pass transistor.
[0015] FIG. 5 illustrates a schematic circuit of an offline AC-low
voltage rectified DC output circuit 200 in accordance with another
embodiment of the present disclosure.
[0016] FIG. 6 illustrates a schematic circuit of the first
depletion high voltage pass transistor 203 and its parallel-coupled
diode 51 which is part of the bridge rectifier 205 when there is no
ballast resistor.
[0017] FIG. 7 illustrates a schematic circuit of the first
depletion high voltage pass transistor 203 and its parallel-coupled
diode 51 which is part of the bridge rectifier 205 when there is a
ballast resistor.
[0018] FIG. 8 illustrates a schematic circuit of an offline AC-low
voltage rectified DC output circuit 300 in accordance with an
embodiment of the present disclosure.
[0019] FIGS. 9a and 9b schematically show a die 400 for an offline
low voltage DC output circuit in accordance with an embodiment of
the present disclosure.
[0020] FIG. 10 schematically shows a method 500 for a layout scheme
for a die shown in FIGS. 9a and 9b in accordance with an embodiment
of the present disclosure.
[0021] FIG. 11 schematic shows a flowchart 600 of a method for
providing a low voltage DC output from an AC offline source in
accordance with an embodiment of the present disclosure.
[0022] The use of the same reference label in different drawings
indicates the same or like components.
DETAILED DESCRIPTION
[0023] Embodiments of circuits for integrated full bridge
rectifiers for offline low voltage DC output are described in
detail herein. In the following description, some specific details,
such as example circuits for these circuit components, are included
to provide a thorough understanding of embodiments of the
disclosure. One skilled in relevant art will recognize, however,
that the disclosure can be practiced without one or more specific
details, or with other methods, components, materials, etc.
[0024] The following embodiments and aspects are illustrated in
conjunction with circuits and methods that are meant to be
exemplary and illustrative. In various embodiments, the above
problem has been reduced or eliminated, while other embodiments are
directed to other improvements.
[0025] The present disclosure relates to integrated circuits and
methods of offline AC-low voltage DC rectification. These
integrated circuits usually comprise of two depletion high voltage
pass transistors and bridge rectifiers, wherein most of the voltage
is dropped across the pass transistor devices, so that other
components in the circuit could be low voltage devices.
[0026] FIG. 2 illustrates a schematic circuit of an offline AC-low
voltage rectified DC output circuit 100 in accordance with an
embodiment of the present disclosure. The offline AC-low voltage
rectified DC output circuit 100 comprises a first input port 101
and a second input port 102 configured to receive an input AC
signal (AC); an output port 106 configured to provides an output
rectified voltage (V.sub.O); a first depletion high voltage pass
transistor 103 coupled to the first input port 101 to receive the
input AC voltage, and based on the input AC voltage, the first
depletion high voltage pass transistor 103 provides a first
voltage; a second depletion high voltage pass transistor 104
coupled to the second input port 102 to receive the input AC
voltage, and based on the input AC voltage, the second depletion
high voltage pass transistor 104 provides a second voltage; and a
bridge rectifier 105 having a first input terminal 105a, a second
input terminal 105b, and an output terminal 105c, wherein the first
input terminal 105a is coupled to the first depletion high voltage
pass transistor 103 to receive the first voltage, the second input
terminal 105b is coupled to the second depletion high voltage pass
transistor 104 to receive the second voltage, and the output
terminal 105C is coupled to the output port 106.
[0027] In one embodiment, the first depletion high voltage pass
transistor 103 comprises a first depletion high voltage JFET; and
the second depletion high voltage pass transistor 104 comprises a
second depletion high voltage JFET.
[0028] In one embodiment, the bridge rectifier 105 further
comprises a fourth terminal 105D coupled to ground.
[0029] In one embodiment, the first depletion high voltage pass
transistor 103 and the second depletion high voltage pass
transistor 104 each has a gate coupled to ground.
[0030] In one embodiment, the bridge rectifier comprises four
diodes. The diodes may be Schottky diodes, regular PN diodes or
base-collector connected bipolar transistors, which is known to one
skilled in the art.
[0031] Because the first depletion high voltage pass transistor 103
and the second depletion high voltage pass transistor 104 have
conductive channels when their gates are connected to ground, when
the absolute value of the input AC voltage is lower than the pinch
off voltage (V.sub.T) of the depletion high voltage pass
transistors, the output voltage (V.sub.O) follows the input AC
voltage; when the absolute value of the input AC voltage is higher
than the pinch off voltage (V.sub.T) of the depletion high voltage
pass transistors, the voltage at the conjunction of the depletion
high voltage pass transistor and the bridge rectifier 105 stays at
the pinch off voltage (V.sub.T) level of the depletion high voltage
pass transistors. As a result, the output voltage (V.sub.O) stays
at the pinch off voltage (V.sub.T) of the depletion high voltage
pass transistors minus the diode voltage drop (V.sub.D), i.e.,
V.sub.O=V.sub.T-V.sub.d. FIG. 3 schematically illustrates the
clipped full-wave rectified output voltage (V.sub.O) and the input
AC voltage (AC) in the offline AC-low voltage rectified DC output
circuit 100 in FIG. 2.
[0032] As illustrated herein before in various embodiments of the
present disclosure, the gates of the first depletion high voltage
pass transistor 103 and the second depletion high voltage pass
transistor 104 are connected to ground, i.e., the substrates of the
first depletion high voltage pass transistor 103 and the second
depletion high voltage pass transistor 104 are connected to ground.
In typical applications, the pass transistor gate comprises a P
type substrate (P-sub) as bottom gate and a separate P type
implant/diffusion as top gate, while the pass transistor channel is
an N type well (N-well), which form a PN junction, as illustrated
in FIG. 4. The top gate and the bottom gate would be connected once
the N-well is pinched. When the PN junction gets forward biased,
minority carriers get injected on both sides (P with an electron
minority, and N with a hole minority). Such unintentional minority
carriers may disturb sensitive circuits, e.g., causing a latch up
or any parametric malfunctions. FIG. 5 illustrates a schematic
circuit of an offline low voltage DC output circuit 200 in
accordance with an embodiment of the present disclosure which
minimizes the "minority injection" or the unintentional generation
of minority carriers.
[0033] The offline AC-low voltage rectified DC output circuit 200
is similar to the offline AC-low voltage rectified DC output
circuit 100. Different to the offline AC-low voltage rectified DC
output circuit 100 in FIG. 2, the offline AC-low voltage rectified
DC output circuit 200 in FIG. 5 further comprises a ballast
resistor 206 coupled between a substrate 207 and ground.
[0034] The operation of the offline AC-low voltage rectified DC
output circuit 200 is described by referring to FIG. 6 and FIG.
7.
[0035] FIG. 6 illustrates a schematic circuit representation of the
first depletion high voltage pass transistor 203 and its
parallel-coupled diode 51 which is part of the bridge rectifier 205
when there is no ballast resistor 206. The first depletion high
voltage pass transistor 203 comprises a diode 31 and an N-well
channel resistor 32 connected as shown. As shown in FIG. 4, the
N-well channel resistor 32 is coupled in series with the diode 51
between the input AC voltage and ground, while the diode 31 is
coupled between the input AC voltage and ground. Since the diode 31
introduces less resistance to current flow, more current flows
through the diode 31 than through the diode 51. Allowing the diode
31 to get forward biased introduces substrate injection. The more
current flow through the diode 31, the more injection occurs. In
addition, other circuits in the same die may also get
interfered.
[0036] FIG. 7 illustrates a schematic circuit representation of the
first depletion high voltage pass transistor 203 and its
parallel-coupled diode 51 which is part of the bridge rectifier 205
when there is a ballast resistor 206. As illustrated hereinbefore,
the first depletion high voltage pass transistor 203 comprises the
diode 31 and the n-well channel resistor 32 connected as shown. As
shown in FIG. 5, the N-well channel resistor 32 is coupled in
series with the diode 51 between the input AC voltage and ground,
while the diode 31 is coupled in series with the ballast resistor
206 between the input AC voltage and ground. The ballast resistor
206 discourages the current flow through the diode 31, thus
minimizing the amount of injection.
[0037] The operation of other parts in the offline AC-low voltage
rectified DC output circuit 200 is similar to that of the offline
AC-low voltage rectified DC output circuit 100.
[0038] In one embodiment, the ballast resistor may be a parasitic
resistor or a defined resistor, e.g. implant resistor, diffusion
resistor, poly silicon resistor, etc. . . . .
[0039] In one embodiment, the ballast resistor may be replaced by
active circuits such as a charge pump circuit. FIG. 8 illustrates a
schematic circuit of an offline AC-low voltage rectified DC output
circuit 300 in accordance with an embodiment of the present
disclosure. The offline AC-low voltage rectified DC output circuit
300 is similar to the offline AC-low voltage rectified DC output
circuit 200. Different to the offline AC-low voltage rectified DC
output circuit 200 in FIG. 5, the offline AC-low voltage rectified
DC output circuit 300 in FIG. 8 comprises a negative charge pump
306 coupled between a substrate 307 and the ground instead of the
ballast resistor 206.
[0040] In one embodiment, all other circuits are placed in an
N-well tub so that the substrate is fully the pass transistor body
and not sharing with other devices of other circuits. The negative
voltage charge pump applies a reverse bias at the pass transistor p
body and N-well channel so that no current flows through.
[0041] The operation of other parts in the offline AC-low voltage
rectified DC output circuit 300 is similar to that of the offline
AC-low voltage rectified DC output circuit 100.
[0042] As illustrated hereinbefore, there are two high voltage
structures in the offline low voltage DC output circuit
100/200/300, which may be integrated into a chip in one embodiment.
As a result, the die area of the offline low voltage DC output
circuit 100/200/300 is highly reduced, which further reduces the
cost.
[0043] The effect of any generated minority carriers may also be
alleviated by layout techniques. FIGS. 9a and 9b schematically show
the top view of a die 400 for an integrated offline low voltage DC
output circuit in accordance with an embodiment of the present
disclosure. The integrated offline low voltage DC output circuit
comprises a plurality of minority generating devices, a plurality
of devices with mergeable NWell, and a plurality of unmergeable
devices, wherein devices with mergeable NWell comprises devices
whose NWell is at same potential as NWell tub, and unmergeable
devices comprise devices whose NWell is at potential different from
NWell tub, non-floating devices (e.g., diodes, bipolar, etc. . . .
). In the example of FIGS. 9a and 9b, the die 400 comprises: a
first site 401, and a second site 402, wherein the first site 401
and the second site 402 are placed on opposite sides of the die to
make their separation distance the farthest possible; an N-well tub
403 between the first site 401 and the second site 402, wherein the
N-well tub 403 serves as a huge minority collector; and a die seal
404; wherein the minority generating devices are placed at the
first site 401 and the second site 402; the devices with mergeable
NWell are group together and placed in the N-well tub 403; and the
unmergeable devices are placed next to the die seal 404 and/or
close to an die edge 405 of the die.
[0044] In one embodiment, the N-well tub 403 serves as a minority
collector. In one embodiment, the minority collector is coupled to
a potential reference.
[0045] In one embodiment, the minority generating devices comprise
a first depletion high voltage pass transistor and a second
depletion high voltage pass transistor.
[0046] In one embodiment, the potential reference is ground.
[0047] In one embodiment, the N-well tub 403 comprises one opening
next to the die seal (and/or close to die edge) to surround
unmergeable devices, as shown in FIG. 9a.
[0048] In other embodiments, the N-well tub 403 may comprise more
than one opening, e.g. 2 openings to surround unmergeable devices
if there are too many unmergeable devices, as shown in FIG. 9b.
[0049] As illustrated above, devices with mergeable NWell are
placed in the N type well 403, and unmergeable devices are placed
next to the die seal 404 (and/or close to die edge 405) surrounded
with the minority collector, so the die seal and/or the die edge
405 may take some of the wandering minority carriers and minimize
the number of carriers from reaching the sensitive devices.
[0050] FIG. 10 schematically shows a method 500 for a layout scheme
for an integrated circuit die shown in FIGS. 9a and 9b in
accordance with an embodiment of the present disclosure. The method
comprises:
[0051] Step 501, placing minority generating devices at a first
site and a second site; wherein the first site and the second site
are placed on opposite sides of the integrated circuit die;
[0052] Step 502, placing devices with mergeable NWell into an
N-Well tub, wherein the N-well tub serves as a minority
collector;
[0053] Step 503, placing unmergeable devices next to a die seal
and/or close to a die edge;
[0054] Step 504, placing sensitive devices as far as possible from
the first site and the second site; and
[0055] Step 505, surrounding unmergeable devices with the minority
collector.
[0056] In one embodiment, the minority generating devices comprise
a first depletion high voltage pass transistor and a second
depletion high voltage pass transistor.
[0057] In one embodiment, the minority collector comprises NWell
tubs. An optional N-type buried layer (NBL) on this NWell tub
further enhances the collection area.
[0058] In one embodiment, sensitive devices comprise diffusion
devices which may be affected by minority carriers.
[0059] FIG. 11 schematically shows a flowchart 600 of a method for
providing a low voltage DC output from an AC offline source in
accordance with an embodiment of the present disclosure. The method
comprises:
[0060] Step 601, receiving an AC input voltage;
[0061] Step 602, generating a first voltage in response to the AC
input voltage;
[0062] Step 603, generating a second voltage in response to the AC
input voltage; and
[0063] Step 604, generating a low voltage DC output by rectifying
the first voltage and the second voltage.
[0064] In one embodiment, in step 602, the first voltage is
generated by a first depletion pass transistor; and in step 603,
the second voltage is generated by a second depletion pass
transistor.
[0065] In one embodiment, in step 604, the rectifying is executed
by a bridge rectifier.
[0066] In one embodiment, both the first depletion pass transistor
and the second depletion pass transistor have a gate connected to
ground, respectively.
[0067] In one embodiment, both the first depletion pass transistor
and the second depletion pass transistor have a substrate connected
to ground via a ballast resistor, respectively.
[0068] In one embodiment, both the first depletion pass transistor
and the second depletion pass transistor have a substrate connected
to ground via an active circuit.
[0069] In one embodiment, the active Circuit comprises a charge
pump.
[0070] This written description uses examples to disclose the
disclosure, including the best mode, and also to enable a person
skilled in the art to make and use the disclosure. The patentable
scope of the disclosure may include other examples that occur to
those skilled in the art.
* * * * *